1. The Owner's Manual for your truck. A lot of these get lost or discarded over the life of the truck, but they have some handy info regarding fluid types and quantities, bulbs and fuses, and a bunch of other things. I have the one that came with the truck, and another I bought (ebay) just to keep here at home. Think about buying one. 2. The GM Factory Shop Manual for your truck. This huge book is one of your truck's best friends. If you've never actually looked at one, do it. They are a little pricey, but worth every single penny, even if you wind up paying new retail price. I wouldn't think of not buying a shop manual for any vehicle that I owned. I've lost count of the number of questions here on this forum that can be answered (though not every question to be sure, but a hell of a lot of them) with some leafing through the shop manual, and sometimes even the owner's manual. They'll probably save you both time and money in the long run.